COLLABORATIONS AND DEVELOPMENT FUND An essential part of the HARC Center will be to enlist a wide range of collaborators to help further identify and validate HIV-host protein complexes, facilitate structure determination of the complexes, utilize structural information to more deeply probe the biological functions of the HIV regulatory and accessory proteins, and extend technological developments in high-throughput expression, structure determination, MS methods, cryo-EM, and tomography. We will facilitate these essential collaborations by: actively reaching out to relevant researchers through direct contacts;organizing visits of collaborators and possible collaborators to the HARC Center to plan future research directions;providing seed funding for promising collaborations; facilitating funding opportunities for collaborators, including the related R21/R33 mechanism announced by NIAID;widely disseminating the goals, results, and available resources of the HARC Center to encourage further outside participation;and actively participating in national and international meetings. We have requested 5% of the direct cost budget for a Collaboration Development Fund to support these activities. Given the breadth of projects encompassed in the initial establishment of the HARC Center, we have solicited letters from potential collaborators working directly on the accessory and regulatory proteins and technologies that comprise the focus of this project. As the HARC Center becomes more established, new research directions will be evaluated thoroughly by the HARC Center Executive Council and internal and external advisory committees, and directions altered and funds allocated as appropriate. Our initial collaborative efforts are described in more detail in Section IV.